Sedimentation apparatus



June 28, 1938. C SCOTT 2,122,385

SEDIMENTATION APPARATUS (LONG AND SHORT TORQUE! ARMS) Filed Jan. 27,1957 4 Sheets-Sheet l Hk H H IO INVENTOR CHARLES H.SCOTT WWW June 28,1938. c SCOTT 2,122,385

SEDIMENTATION APPARATUS (LONG AND SHORT TORQUE ARMS) Filed Jan. 27, 19374 Sheets-Sheet 2 INVENTOR CHARLES H. SCOTT ATTORNEY.

June'zs, 1938.

c. H. SCOTT 2,122,385 SEDIMENTATIQN APPARATUS (LONG AND SHORT TORQUEARMS) Filed Jan. 27, 1937 4 Sheets-Sheet s INV'ENTOR.

BY UHARLE: H.5co'rt ATTORNEY June 28, 1938. c. H. scoTT 2,122,385

SEDIMENTATION APPARATUS (LONG AND SHORT TORQUE ARMS) Filed Jan. 27, 19374 Sheets-Sheet 4 W" v m 1 N INVENTC CHARLES H SCOTT ATTORNEY;

UNITEDSTATES PATENT OFFICE SEDIMENTATION APPARATUS (LONG AND SHORTTORQUE ARMS) Charles 11. Scott, Queens Village, N. Y., assignor to TheDorr Company, Inc., New York, N. Y.,

a corporation of Delaware Application January 2'7, .1937, Serial No.122,511

5 Claims. (Cl. 210-55) The present invention relates to sedimentationtion are, of course, respectively larger than the units having what isfrequently referred to as corresponding diameters of the annular inlyingclarifying settling or thickening tanks in which section. Thecooperating or'combined raking of a sediment raking mechanism disposedover the the two arms is toward a centrally or inwardly 5 tank bottomfunctions incident to a turning disposed sediment discharge. 5 thereofto effect a raking and transfer of sedi- The sedimentation units towhich the present merited or settled solids to a discharge sectioninvention is directed are for use in many fields of the tank. Theinvention according to one of industry such as in metallurgical fieldsfor the aspect thereof relates to a unit in which the recovery ofmetallurgical pulp from liquid misisediment raking mechanism comprisesrake arms .tures containing same or for the elimination of 10 that arepivotally mounted on and in respect to settled solids such as silt fromwaters containing a horizontally turnable cage or arm-carrying the sameand in many other fields which might structure so that upon rakingelements of a pivbe mentioned. otally supported arm encountering anobstruc- Each pivotally mounted arm is supported from in effect alagging or rearward swinging movehinges which are vertically andhorizontally ment of the outer end of the particular arm spaced andarranged with the pintle axes in relative to the supporting carriertherefor as the alignmen along l vin a downward 0r latter movesforwardly. rearward slope or inclination with respect tothe 20. Thepresent invention revolves about a sediforward horizontal rakingmoveinent of the arm- -ment raking mechanism in which there areemcarrying structure whereby upon an obstruction ployed rake armconstructions or rakearms of being encountered there is permitted alifting different lengths some of which may be referred movement of thefree or swinging end of .the to as long arms while others thereof may bepivoted arm and a lagging or relative rearward referred to as shortarms. These arms are prefmovement of the free end of the arm withrespect 25 erably symmetrically arranged-and disposed in to the carrierwhich continues its forward moverespect to the carrying structuretherefor and ment. In the arrangement just described the at least thelong arms are pivotally mounted so raking. blades on the arms haverearward and as to permit a swinging movement as above deinwardinclination with respect to their forward scribed in respect to thecarrying structure. The p hs of m e e 30 short arms may be but are notnecessarily piv- According to an underlyin feature of the P otallymounted as this feature is to be determined ent invention the rakingelements on each pivaccording to the desires of a designer or operatorally-mount d lo 8 rake are disposed for of a particularinstallation. Thelong arm is essentially rak y an outlying section 0 preferably providedwith raking elements disas otherwise expressed. e raking elements 35posed along only theouter end section thereof, each pivotally-mountedlong arm are disposed or, as might be, described along the major porsoas to avoid raking a substantial portion of the tion thereofparticularly along the outer end in y ng tank bottom section. sectionthereof. The short arms are provided for One main fea u e of theinvention revolves 4o raking the section of the tank bottom which isabout a sediment raking mechanism as an article 40 not raked by the longarms due to the omission of manufacture particularly suitable for use ina of effectual raking elements along the inner end sedimentation orthickening tank and which raksection of the long arms. I ingmechanismincludes in associated relationship An important and underlying featureof the p v ta y u t long rake arms essentially present invention residesin the fact that the fective for accomplishing araking operation only 45short arm is provided with raking elements or along the outer section ofa tank bottom thereof means, to wit, a series of raking blades foressenand stub or short arms disposed-for completing tially functioningover what may be viewed as an the work by performing a raking operationover annular inlying section of a settling tank bottom the inner sectionof the tank bottom.

while the pivotally-mounted long arm is pro- The invention possessesother objects and fea- 50 vided with raking elements or means, to wit,a. tures of advantage, some of which with the foreseries of rakingblades for essentially-functioning going will be set forth in thefollowing descripover only what may be viewed as an annular tion. In thefollowing description and in the outlying section of the tank bottom.The inner claims, parts will be identified by specific names and outerdiameters of the'aimular outlying secfor convenience; but they areintended to be as 55 tion there is permitted an automatic upward and itscarryin structure through e medium f 15' generic in their application tosimilar parts as the art will permit. In the accompanying drawdischargefor the ings there has been illustrated the best embodiment of theinvention known to me, but such embodiment is to be regarded as typicalonly of many possible embodiments, and the invention is not to belimited thereto.

The novel features considered characteristic of my invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and its method of operation,together with additional objects and advantages thereof, will best beunderstood from the following description of aspeciflc embodiment whenread in connection with the accom: panying drawings in which:

Fig. 1 is a plan view of a sedimentation or thickening tank showingtherein a sediment raking mechanismby which the present invention isrealized;

Fig. 2 is a sectional elevation of the tank shown in Fig. 1 and is aview taken as on the broken line 2-2. looking in the direction ofthe'arrows and with one each of the long and short rake arms inelevation;

Fig. 3 is a plan view enlarged as compared with Fig. 1 andshows aportion of the central part of Fig. 1 and illustrates the pivotalmounting of the long and short rake arms;

Fig. 4 is a schematic view graphically illustrating the areasrespectively swept by the rakingblades of the long and short arms;

Fig. 5 is an elevation considerably enlarged as compared with Fig. 1 andshows a portion of the centrally arranged pier about which thearmcarrying structure turns and in this figure there is clearlyillustrated the pivotal or hinge mounting for the inner ends of the longand short arms and also an adjustable stop means which is relied uponfor determining the lowermost operaative position of the arms relativeto the arm- 'carrying structure; and

Fig. 6 is a plan view enlarged as compared with Fig. 1 showing therelation of the raking blades of the long and short arms. In this figurethe short arms are shown as fixedly secured to the carrying structuretherefor; otherwise the arrangement and details of the parts thereof arethe same as in a construction in which-the short arms are pivotallymounted.

Reference will now be made to the drawings in detail.

In the drawings l0 designates a settling tank suitable for use in asedimentation unit of general application. Such tank is' preferablycylindrical, or at least of a form devoid of sharp vertical corners andof a horizontal internal cross section between that of a square as onelimiting form and that of a circle as the other limiting form. Thetankhas a bottom ll sloping downwardly at any desired angle to a centralwell or sump l2 for receiving sedimented solids passed thereto by thesettled solids raking mechanism which functions within the tank.Connected to the section providing the central well or sump and leadingfrom the bottom thereof is asettled solids withdrawal pipe l3 providingasediment tank. Adjacent the f top or upper portion of the tank l0 andextendirig along the periphery thereof there is provided a trough llconstituting an eflluent launder which with a discharge pipe [5 leadingtherefrom constitutes a supernatant liquid withdrawal means. An upperedge portion of the trough or launder- I4 provides a weir over which thesupernatant liquid flows into the trough and this weir determines thenormal operative level of the body of liquid underoing sedimentationwithin the tank. Any suitable infiuent pipe or conduit constituting atank feeding means can be employed and such conduit is designated by I6.In the construction shown this influent pipe is provided by a stationarypier I 1 which is made hollow whereby the liquid solids mixture which isfed upwardly through the pier is delivered into the central section ofthe sedimentation tank and from which the liquid passes at a gradual andprogressively decreasing flow rate to the marginal launder. Thisarrangement permits an early settling of readily settleable solids inthe central regions of the tank and allows for a progressive settling ofthe less readily settleable solids as the liquid passes toward themarginal walls of the tank It will be noted thatin accordance with thequantity of liquid solids mixture fed into the tank through the feedpipe or conduit Hi there is a consequent and corresponding quantity ofdischarge of supernatantliquid into the, trough and thence from thesedimentation unit. The pier l1 extends upwardly from the bottom of thetank and is preferably centrally disposed with respect to the marginalwall of the tank and the well or sump I2 is disposed adjacent to thebase of this pier. The pier may be viewed as a stationary upstandingpedestal and'it carries at the top thereof a stationary bearing memberi8 and an upward extension constituting a stationary platform I9.

.edon the stationary bearing member I 8 so as to rotate about avertically extending axis concentrio with the pier when driven by themotivating means 20. The turnable bearing member supports a dependingarm-carrying structure 24 from the lower portion of which there are car-7 ried long rake arm constructions 25 and short The depending armrakearm constructions 26. carrying structure is preferably provided by aframework or cage and surrounds the pier H. The rake arm constructions,particularly the long rake arm constructions, are pivotally supportedthrough the medium of hinges arranged, as will be presently described indetail, so as to permit upward and rearward swingingmovements of thefree or outer ends of the arm constructions. The pivoted armconstructions when in their lowermost positions derive support not onlythrough themedium of the hinges, but also through the adjustable stopmeans interposed between each arm construction and the arm-carryingstructure as will presently appear.

The arm-carrying structure 24 is provided by the framework or cage thatis made up of wrought metal in the form of rolled structural shapes suchas vertically'extending angle irons tied together and connected byhorizontal members and diagonal braces whereby a relatively rigidskeletontype of structure results. This framework or cage is preferablynon-cylindrical and in fact is preferably square in horizontal ferred toas the long rake arms and on the other ,two and opposite faces there aremounted, preferably but not necessarily pivotally mounted, the shortrake arms. The long and short arms 25 and 28 are made so as to comprisein assembled relationship relatively long structural shapes such asrolled angles or tees constituting members which are sometimes referredto aslongitudinals and which are tied together by gusset plates andtransverse braces. The arm constructions are preferably triangular invertical cross section. "The long arms 25 are of a length to have theouter ends terminate adjacent to or in the immediate vicinity of theinner face of" the upstandingmarginal wall 21 of the tank II).

To the under surface or at-the lower section of the long arms 25 areattached or embodied raking blades 28. The blades 28 are so arranged asto rake or move the sediment or sludge on the bottom of the tank towardthe central portion of the tank bottom. The raking blades 28 of the longarms 25 are arranged ineffect parallel to each other and are disposed soas to occupy approximately two-thirds of the length of the arms measuredinwardly from the outer ends thereof. The short arms 26 areapproximately one-third the length of the long arms 25 and are providedwith or embody raking blades 28. The raking blades 29 are disposed atand throughout the entire length of the lower portion of the short arms.Normally the raking blades 28 and 29 are disposed above but proximatethe bottom ll of the tank. The raking blades may be viewed as rakingelements provided by and as constituting a part of the rakingarnrconstructions. to-

which they correspond.

As to the pivotal or hinge mounting for the long and short arms this isclearly indicated and shown in and by the several figures thereof butparticularly in and by Fig. 5.

In the form as illustrated by Figs. 1, 2. 3 and each of the arms isprovided with horizontally and vertically spaced hinges 30 and 8|, thehinge member 30 being a lower hinge member which is sometimes referredto as a rear bottom hinge and the hinge 3| being an upper hinge memberwhich is sometimes-referred to as a front upper hinge.

1 The pintle axes 32.and 33 of the hinges 3|! and 3| are in alignment,to wit, along a downwardly and rearwardly inclinedllne as shown in Fi 5.Each of the hinges comprises a fixed leaf 34 which is secured to a faceof the square framework or cage constituting the arm-carrying structure,anda sw'ingable leaf 35 to which the inner end of the rake armconstruction is connected, to wit, in the immediate. region or vicinityof a main longitudinal of the arm construction. The fixed leaf of eachhinge is preferably but not necessarily connected to the framework inthe immediate vicinity where the vertical structural members or verticalcorner members have connections with horizontal tie members and braces.The hinges 38 and 3| provide the pivotal support for the swinging armconstructions and because of the inclination of the pivotal axes of thehinges as a set there is permitted the upwardand rearward movementof thefree end of the rake arm constructions thus carried by'the particularset. Each of the pivotal arm constructions, to wit, long arms 25 or theshort arms 28 as the case may be is provided with a suitable low limitstop construction 88. This stop construction is functionally disposedbetween the arm-carrying structure or cage 24 on the one hand and theswinging rake arm constructions 25 or 28 as V the case may be on theother hand. In the arrangement shown the low limit stop is provided by athreaded bolt 31 that is carried in 9. corresponding threaded section ornut 38 which in effect serves as a bolt carrying member located in theimmediate vicinity or region of the inner end of a lower forwardlongitudinal of the rake arm hinges corresponding thereto provide whatmay be viewed as an intermediate means or mechanism by which eachpivotal arm construction derives its support from the arm-carryingstructure. It will also be manifest that the bolt lflcan be relied uponto adjust the position of the rake arm constructions and consequentlythe raking blades 28 or 28 as the case may be in relation to the bottomll of the tank.

The hinge constructions above described will permit the arms 25 and 26to tilt on or about the pintle axis which lies at an angle to the axisof rotation of the square framework or cage 2|. As the raking blades 28and 28 on the arms 25 and 28 respectively encounter an obstruction sucharms will-rotate or tilt on their axes relative to the rakingsupporttherefor and the outer ends will lift and consequently assumeupward and rearward positions relative to the framework or cage 24 whichof necessity duringthe normal operation thereof will continue itsforward rotation movement. As above stated the forces which produce thelifting of the outer end of a particular arm has both radial andtangential components and because of the length of the long arm atangential component produces a greater lifting influence on a long armthan it does on a short arm. Figure 4 illustrates. graphically the areaof the bottom ll of the tank which is swept over by the blades 28 and28. The outer groups of circles 82 of said figure mark the area sweptover by the blades- 28 of the long arms 25 while the inner group ofcircles 48 mark the area swept by the blades 28 of the short arms 25.

The hinges of the short arms are shown at the same heights on theframework or cage 28 as the hinges of the long arms 25. This is prima- Irily for convenience. It is possible to have the upper hinges for theshort arms higher than is practical or necessary for the long arms, thisin order that advantage of a longer vertical arm .may be desired for usein conjunction with the radial component required for lifting the arms.

This same effect .may be accomplished by posithe short arms. Theposition of these hinges, 7s

however, is largely a question of design in so al in respect to the i.aras the requirements of a particular hinge arrangement or installation isinvolved. In generthe upper hinges should have the same elevation, thelower hinges should have the same elevation,

and there should be the same horizontal spacing as between the front andrear hinges of each of the several sets whereby the arms may be madeinterchangeable.

The construction shown inFig. 6 is substantially the same as that ofFigs. 1, 2 and 3 with the exception that according to the arrangement ofFig. 6 the short arms are fixedly secured to the carrying structuretherefor, to wit, to the cage 24. This Fig. 6 clearly shows in plan therelationship of the raking blades as employed on the long arms and asemployed on the short arms, and also the position of the blades of thelong arms as compared with; the raking blades of the short arms. v Thehorizontally-movable arm-carrying structure 24 of thesettled solidsraking assemblage may be viewed as a unidirectional horizontallyturnablerake-arm construction that continuously moves forwardly within or alonga closed path whereby due to said movement the pivotally mounted longarms rake an outer annular or closed portion of the bottom or floorsection of the tank and whereby short or stub arms rake an inner annularor closed portion of the bottom or floor portion of the tank. The rakingmeans or blades on the long arm are disposed so that they leaveessentially unraked thereby substantial portions of the inner annularfloor section with the result that each of the rake arms perform a partof the work of raking the floor" bottom and with the result that boththe long and shortrake arms are essential to the raking and transferringof sedimented solids to the inwardly or centrally disposed sedimentdischarge. The sediment discharge sump l2 herein described is locatedimmediately below or in the immediate vicinity of the lower end of thisarm-carrying structure 24. The inner annular floor section mentioned islocated next to and merges into the sediment discharge sump and it maybe properly described as locatedproximate the region in which thearm-carrying structure moves.

I claim: 1. A- sedimentation unit comprising a tank having-a bottom withmarginal wall, means for sup-plying a liquid-solids mixture to the tank,supernatant liquid withdrawal means leading from the upper portion ofthe tank: and a sediment discharge leading frem the central lowerportion of the tank; and in association with the foregoing a sedimentraking mechanism having a unidirectional horizontally-turnablearm-carrying-structure and outwardly extending rake arms supportedthereby and provided for cooperatively coilecting and transferringsedimented material from diverse sections of the tank bottom to saidsediment discharge; which said rake arms comprise short rake armsprovided with blades for raking= 'onlyzan inlying annular section of the-tank :botto m and also long pivotally mounted- '1. rake arms extendingoutwardly into a region beyond that: traversed by the raking blades ofthe short "rake-armsand provided with blades disposed for raking. onlyan annular floor section of the diameters are relatively large ascompared with hinges of the several sets,

.tankbottom of which the inner and'outer' larly disposed so as toessentially leave unraked nular floor section, each pivotally-mountedrake arm being supported from the arm-carrying structure through themedium of vertically and horizontally spaced hinges arranged with thepintle axes in alignment along a line having a downward and rearwardslope.

2. A sedimentation unit comprising a tank having a bottom with marginalwall, means for supplying a liquld=solids mixture to the tank, asupernatant liquid withdrawal means leading from the upper portion ofthe tank, anda sediment discharge leading from the central lower.portion of the tank; and in association therewith a sediment rakingmechanism having an armcarrying structure horizontally-movable along aclosed path and .a set of outwardly extending rake arms supportedthereby and provided for collecting and transferring sedimented materialfrom diverse sections of the tank bottom to said sediment discharge;which said rake arms com prise a stub arm having raking means disposedfor functioning only over an inlying floor section of the tank that isproximate the path along which the arm-carrying structure moves, and apivotally-mounted arm extending into a region outwardly beyond thattraversed by the stub arm and having raking means disposed for.functioning over a floor section of the tank of which the inner andouter diameters are relatively large as compared with the correspondingdiameters of the aforementioned inlying floor section and furthermoreparticularly disposed so as to leave essentially unraked thereby asubstantial portion of the inlying floor section; said pivotallymountedarm being supported from the armcarrying structure through the medium ofvertically and horizontally spaced hinges arranged with the pintle axesinv alignment along a'line having downward and rearward slope.

3. A sedimentation unit as defined in and by claim 2 wherein the stubarm is short with raking means disposed substantially along the en-'tire length thereof and has rigid connection with the arm-carryingstructure and wherein the pivoted arm is long with raking means disposedalong only the outer end section thereof.

4. A structure as defined in and by claim' 2 as a main claim wherein theraking means are provided by sets of raking blades arranged along thearms to which they correspond and in spaced relationship with respect toeach other and have rearward and inward inclinations for effecting stepby step inward raking movements; and according to which each rake arm ispivotallymounted and is supported from the arm-carrying structurethrough the medium of hinges as defined in and by the main claim.

.5. A sediment raking assemblage for employment in a settling tankhaving a stationary supporting means; which raking assemblage comiiiprises in combination an arm-raking structure the tank bottorn and ofwhich others are long and pivotally-mounted with the swinging endsthereof extending into aregion outwardly beyond that traversed by theshort arm and have raking elements essentially disposed relative to theraking elements of the short arms for raking an outlying section of thetank bottom and for transferring settled material to and under operativeinfluence of the raking elements of the short armsrthe raking elementsof the long arm also 10 being essentially disposed so as to leaveunraked thereby a substantial portion of the aforementioned inlyingsection of the tank bottom; the means by which the long arm ispivotaliy-supported from the arm-carrying structure being provided 'byvertically and horizontally spaced hinges arranged so that the pintleaxes are in alignment along a rearwardly and downwardly sloping line.

CHARLES H. sco'rr. 10

